Critics faulted the research for not adequately considering the content of the TV watched, but experts said it bolsters advice that children shouldn't have TVs in their rooms.

The separate findings were published Monday in the July issue of Archives of Pediatrics & Adolescent Medicine.

One of the studies involved nearly 400 northern California third-graders. Those with TVs in their bedrooms scored about eight points lower on math and language arts tests than children without bedroom TVs.

A second study, looking at nearly 1,000 adults in New Zealand, found lower education levels among 26-year-olds who had watched lots of TV during childhood.

A third study, based on nationally representative data on nearly 1,800 U.S. children, found that those who watched more than three hours of television daily before age 3 scored slightly worse on academic and intelligence tests at ages 6 and 7 than youngsters who watched less TV. The effect was only modest but still worrisome, said co-author Frederick Zimmerman, a researcher at the University of Washington.

The studies took into account other factors that might have influenced the outcome, such as household income. But they largely ignored other research that ``found positive associations between children's educational TV viewing and subsequent academic achievement,'' according to an Archives editorial.

``Reliable and valid estimates of viewing, including content-based measures, are critical to our understanding of the effects of TV on young children, especially children younger than age 2 years,'' the editorial said.

Previous research has linked television exposure in young children with attention problems and difficulty learning to read.

The American Academy of Pediatrics recommends that youngsters under age 2 not watch any television, that older children watch no more than two hours daily of ``quality'' programming, and that televisions be kept out of children's bedrooms.

Recent data suggest, however, that U.S. youngsters from infancy to age 6 watch an average of one hour of TV daily, and that 8-to-18-year-olds watch an average of three hours daily.

John Wilson, senior vice president of programming at PBS, released a statement saying that other studies have shown that the Public Broadcasting Service's children's programs, which include ``Sesame Street,'' can benefit child development.

``As overall media usage increases among young children ... further research and study on media's impact on child development is needed,'' Wilson said.

The New Zealand study led by Dr. Robert Hancox of the University of Otago in Dunedin acknowledged that the results don't prove that TV is the culprit and don't rule out that already poorly motivated youngsters may watch lots of TV. But the authors said they don't think that explains their results.

Their study measured the TV habits of 26-year-olds between ages 5 and 15. Participants with college degrees had watched an average of less than two hours of TV per weeknight during childhood, compared with an average of more than 2 hours for those who had no education beyond high school.

In the California study, children with TVs in their rooms but no computer at home scored the lowest, while those with no bedroom TV but who had home computers scored the highest, according to researchers Dina Borzekowski of Johns Hopkins Bloomberg School of Public Health and Dr. Thomas Robinson of Stanford University.

``While this study does not prove that bedroom TV sets caused the lower scores, it adds to accumulating data that kids shouldn't have TVs in their bedrooms,'' Robinson said.